1. THEROTICAL ASPECTS OF TRASDERMAL DRUG DELIVERY SYSTEM

2. Introduction:-
Introduce to overcome the difficulties of drug delivery through oral route.
Patients often forget to take their medicine, and even the most faithfully compliant get tired of swallowing pills, especially if they must take several each day.
By passing the gastrointestinal (GI) tract would cause the GI irritation that frequently occurs and avoid partial first-pass inactivation by the liver.
The transdermal therapeutic systems (TTS) are more convenient to use than that of the other formulations.

3. Currently Available TDDS:-
Scopolamine (hyoscine) for motion sickness.
Clonidine and nitroglycerin for cardiovascular disease.
Fentanyl for chronic pain.
Nicotine to aid smoking cessation.
Transdermal glyceryl trinitrate for acute stroke therapy.
Sufentanil patch for chronic cancer pain.

4. Advantages Of Transdermal Drug Delivery System:-
Easy elimination of drug delivery during toxicity.
Avoidance of first pass metabolism of drugs.
Self administration is possible.
Topical patches are a painless.
Topical patches have fewer side effects than oral medications or supplements.

5. Disadvantages of TDDS:-
The possibility of local irritation may develop at the site of application.

6. Generations of TDDS introduced by Prausnitz:-
1st generation:
TDDS include traditional patches such a clonidine or estrogen.
2nd generation:
TDDS include patches plus some type of enhancers to improve drug delivery.
3rd generation:
TDDS use novel technologies to increase the scope of molecules that can be delivered through the skin.

7. Anatomy of Skin:- Epidermis:- Epidermis is outer most layer of skin.
It can be sub-divided into five layers.
Dermis:-
3-5 mm thick layer.
It provides nutrient and O2 to skin.
Hypodermis:-
Hypodermis fat tissue supports the dermis and epidermis.
Fig1:- Structure of Skin

8. Fig2:- various layer of epidermis
Fig3:- A multilayer skin model showing sequence of transdermal permeation

9. Pathways Of Drug Absorption Through The Skin:-
Transfollicular route
Transcellular route
Intercellular route
Fig4:- Skin showing route of absorption

10. 1. Transfollicular route:
Shortest pathway
It provides large area for difussion of drug
Eg. Sodium Fluorescein
2. Transcellular route:
Drug passes from corneocytes of stratum cornea.
This route suitable for hydrophilic drug.
3. Intercellular route:
Drug passes the alternating lipid and aqueous domain by portitionating into lipid bilayer diffuse into inner side
Suitable for uncharged lipophilic drug

11. PERMEATION ENHANCERS:-
A) Chemical Approach:
Solvents
Terpenes, terpenoids and essential oils
Fatty acids and esters
Surfactants
Prodrug approach
B) Physical Approach:
Abrasion
Electroporation
Iontophoresis
Laser Radiation
C) Particulate system:
Liposome

12. Techniques for TDDS:- A) Structure-based enhancement techniques
Transdermal Patches
Metered-Dose Transdermal Spray (MDTS)
B) Electrically-based enhancement techniques
physical approaches of permeation enhancers
C) Velocity -based enhancement techniques
Powderject Device

13. Types of Transdermal Patch:-
a) Single Layer in Adhesive
b) Multi-Layer in Adhesive

14. f) Micro reservoir system
c) Vapour Patch
d) Reservoir system
e) Matrix system
i) Drug in adhesive system
ii) Matrix-dispersion system
f) Micro reservoir system
Fig7:-Vapour Patch

15. Transdermal Drug:- Approval year Drug Indication Product Name
Marketing Company
1979
Scopolamine
Motion Sickness
Transderm-Scop
Novarties Consumer Health (Parsippany, NJ)
1984
Clonidine
Hypertension
Catapres-TTS
Boehringer Ingelheim (Rigefield, CT)
1990
Fentanyl
Chronic pain
Duragesic
Janssen pharmaceutica (Titusvilla, NJ)
1991
Nicotine
Smoking cessation
Nicoderm, Habitrol, ProStep
GlaxoSmithKine (Philadelphia, PA)

16. Preparation Of TDDS:- Preparation of TDDS by using proliposomes
Free film method
Mercury substrate method
“IPM membranes” method
“EVAC membranes” method
Aluminium backed adhesive film method

17. Evaluation of Transdermal Patches:-
Thickness
Percentage Moisture content
Percentage of moisture uptake
Flatness
Drug content analysis
Skin irritation study
Quick stick (peel-tack) test
Stability studies
In Vitro skin permeation study
In vivo Studies

18. Conclusion:-
Transdermal drug delivery is hardly an old technology, and the technology no longer is just adhesive patches. Advances in drug delivery systems have increasingly brought about rate controlled delivery with fewer side effects as well as increased efficacy and constant drug delivery.
Now a day’s Transdermal drug delivery systems are used for hormonal drugs and insulin.

19. REFERENCES:-
Aulton M.E, Pharmaceutics, the Science of Dosage Form Design, 2nd Edition, Elsvier Publisher, 2002,
Babiuk S, Baca-estrada M, Babiuk LA, Ewen C, Foldvari M. J Control Rel 2000; 66:
Dipen Patel, Sunita A. Chaudhary, Bhavesh Parmar, Nikunj Bhura, ”Transdermal Drug Delivery System: A Review” Arihant School of Pharmacy and Bio-Research Institute, Gandhinagar, Gujrat, India.
Mezei M, Gulasekharam V. Life Sci 1980; 26:
Nat Biotechnol,2006 Nov; 26(11):

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